1. Field
The technological field relates to a grid-connected power storage system and an integration controller thereof. More particularly, the technological field relates to a grid-connected power storage system with a simple circuit, and an integration controller thereof.
2. Description of the Related Technology
Recently, the European Union (EU) has settled on a plan to increase the percentage of renewable energy of all electricity generation sources to 20% by the year 2020 and 50% by the year 2050. The US is planning to perform renewable portfolio standards (RPS). Since the percentage of renewable energy among all electricity generation sources is expected to increase to 30% to 40% in the future from the current rate of 5%, a power system should prepare for such a new change.
However, it is not easy to control the amount of electricity generation of renewable energy because the amount of electricity generated attributable to renewable energy is dependent on fluctuating natural conditions such as sunlight, wind power, and wave power. Thus, a method for overcoming a decline in power quality that may occur due to fluctuation of the renewable energy and in homogeneity between production and consumption time is undergoing research. The power quality may be evaluated based on voltage and frequency. When the supply amount and the demand amount of the renewable energy are not equal to each other in real time, abnormalities occur in voltage and frequency so that power quality of the entire power system may be deteriorated. Therefore, a system of electricity generation of renewable energy which addresses these abnormalities is desirable.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.